The present invention relates to a novel pipette mechanism which includes a transducer for monitoring the position of the piston within the pipette chamber.
Mechanically operated pipettes greatly simplified the titrating and pickup of volumes of fluid. These pipettes included a manual device for setting the desired volume to be picked up or dispensed by the pipette. However, the proper use of mechanical pipettes depended, to a great extent, on the skill of the operator. For example, the user's thumb regulated the speed of the piston within the mechanical pipette on the uptake stroke. Permitting the piston to move to quickly in this mode caused inaccurate dispensing of the fluid taken up by the pipette. Such inaccuracies generally increase with the fatigue of the pipette operator. In addition, the mechanical pipette simply functions to dispense a preset volume of fluid. Moreover, the determination of this setting required turning of a lead screw which is relatively tediuos and time consuming.
U.S. Pat. No. 3,857,092 describes an electrical system using a differential capacitor transducer which is generally applicable to micrometers and other measuring equipments. There is no known prior art which continually determines the amount of liquid being held by a pipette in operation.